Background & Aim: Bacterial meningitis after brain surgery is rare but serious. The present study was undertaken to determine the frequency of postcraniotomy meningitis, identify etiologic agents, and analyze the risk factors. Patients & Methods: This descriptive cross-sectional study was conducted at Firoozgar Hospital from 1999 to 2004. Data was analyzed by SPSS software(version 11.5). Results: Out of 233 patients undergone craniotomy, 11 patients(4.7%) suffered from meningitis. CSF culture was positive in 4 cases and all of them were gram negative bacilli(Klebsiella in 3 cases and E.coli in one case). Several risk factors including external ventricular device, CSF leak, V-P(Ventriculo-Peritoneal) and V-A(Ventriculo-Arterial) shunt were identified by univariate analysis. There was only a significant statistical correlation between postcraniotomy meningitis and repeating the operation(P<0.05). Conclusion: Nosocomial infections including postcraniotomy meningitis are serious problems in hospital, therefore, all of the health care workers should be educated about prevention of infections(like hand washing, disinfection and sterilization of instruments and rational use of antibiotics).